fix function name access

Co-authored-by: Conor MacBride <[email protected]>

Author: astrofrog

pytest_arraydiff/plugin.py

@@ -311,7 +311,7 @@ def pytest_runtest_call(self, item):
         filename = compare.kwargs.get('filename', None)
         if filename is None:
             if single_reference:
-                filename = item.function + '.' + extension
+                filename = item.function.__name__ + '.' + extension
             else:
                 filename = item.name + '.' + extension
                 filename = filename.replace('[', '_').replace(']', '_')